Cement troweling apparatus



Patented Mar. 24, 1942 CEMENT TROWELING APPARATUS Roy A. Conway,Inglewood, Calif., assignor to Steelform Contracting Company, SanFrancisco, Calif., a corporation of California Application August 30,1940, Serial No. 354,790

Claims. l (Cl. 94-45) This invention relates generally to apparatus forperforming troweling or floating operations on cementitious mixtures,such as wet mixtures of Portland cement.

An object of the invention is to provide troW- eling apparatus which canbe quickly and readily adaptable by simple adjustments to suit varyingconditions. In this connection, the invention is characterized by theuse of troweling blades carried by a rotatable structure and normallydispos-ed at an inclination to the plane of operation, together withadjusting means Whereby an operator can simultaneously change the angleof inclination of each of the blades.

Another object of the invention is to provide a trovveling device ofrelatively simple construction which can be readily manufactured, andwhich will be capable of relatively severe usage without necessitatingfrequent repairs or replacements.

Additional objects will appear from the following description in whichthe preferred embodiment of the invention has been set forth in detailin conjunction with the accompanying drawings.

Referring to the drawings:

Figure 1 is a side elevational view illustrating a machine incorporating`the present invention;

Figure 2 is a plan view of the machine shown in Figure 1, but with thetroweling blades turned to a horizontal position to facilitateillustration;

Figure 3 is a cross sectional detail taken along the line 3-3 of Figure2;

Figure 4 is a detail taken along the line 4-4 of Figure 3, and showingthe manner in which each blade normally engages the surface beingtroweled;

Figure 5 is a cross sectional detail on an enlarged scale taken alongthe line 5 5 of Figure 2;

Figure 6 is a cross sectional detail taken along the line 6-6 of Figure5; and

Figure 7 is a cross sectional detail taken along the line l-l of Figure6.

The machine illustrated in the drawings consists of a rotatablestructure I0', adapted to be driven by a motor II. The rotatablestructure carries a plurality of troweling elements or blades I2 whichare adapted to operate upon a flat or horizontal surface, such as thesurface I3 in Figure 1.

The rotatable structure Il) preferably includes an inner hub I4 in theform of a hollow annular casing, together with an outer circular rim I6,which is secured to the hub by means of radial struts Il. A plate I8 isattached to the upper side of the hub I4, and is coupled to the driveshaft of the electric motor II. Thus the structure I0 serves to supportthe motor, and the motor in turn rotates the structure over the surfaceto be troweled or floated. A suitable handle I9 is attached to thehousing of the motor, so

that an operator may progress the machine over a floor surfacing. y

rlhe blades I2 are formed of spring metal, comparable to the materialusedin making hand floating trowels.v The mounting means for the bladesI2 includes the square shaftsZI, which are radially disposed, and whichhave their inner end portions 22 extending through the side Wall of thehub I4, and journaled thereto. The outer ends of the shafts arejournaled in suitable castings or bearings 23, which are mounted uponthe rim I6.

As a means for simultaneously adjusting the angular positioning of allof the shafts 2I, the inner end portion of each shaft is secured to asegmental gear 24, located Within the hub I4. Set screws 24a serve toretain each gear 24 at a desired angle with respect to its associatedshaft. The segmental gears all mesh with a ring gear 2S, which is seatedwithin the hub, and Which can be turned relative to the hub. Asrepresentative of suitable adjusting means which can be manipulated bythe operator, I have shown an adjusting screw 28 extending through anopening 29 in one side of the hub. Mounted Within the opening 29, thereis a pintle 3I through which the screw 28 extends and to which it isjournaled.

The-inner threaded end portion 32 of screw 28 engages a nut 33, and thisnut has one end directly connected to the ring 2S by a pivot pin 34, andits other end connected by pivot pin 36 to a yoke 3l, which in turn isrigidly attached to the ring 26. Turning of screw 28 changes the angularsetting of ring 26 with respect to the hub, and this in turn causessimultaneous rocking movement of each of the shafts 2 I.

Suitable means, renabling individual adjustments of each blade, isemployed for attaching the blades tothe shafts 2 I Thus the advancingedge of each blade is attached to a rigid reinforcing bar 39, and thisbar is secured to the lower ends of the studs 4I and 42. Both of thesestuds extend through openings provided in the associated shaft 2l. Stud4I carries a spacing collar 43 interposed between shaft 2I and theadjacent part of bar 39, whereby upon turning down nut 44, bar 39 can beclamped against collar 43 and held rigidly with respect to the shaft.Near the stud 42, shaft 2l is threaded to receive an adjusting screw 46,the lower end of which engages the upper face of bar 39. By adjustingscreW 46, the height of the outer end f bar 39 with respect to shaft 2Ican be adjusted, and any given adjustment can be retained by tighteningnut 4l on stud 42.

It will be noted from Figure 2 that the trailing edge 48 of each troWelblade I2 is at an angle to the axis of its corresponding shaft 2|, andalso inclined slightly with respect to radii taken from the center ofrotation of the structure. Therefore, in order to have the trailingedges 48 bear evenly upon a fiat surface I3 to be troweled, when theblades are tilted as shown in Figure 1, the outer portion of eachmounting bar 39 may be raised somewhat with respect to its inner end, asshown in Figure 3.

Operation of the machine described above can be briefly outlined asfollows: 'I'he machine is placed upon a surface to be troweled, which isusually a floor surfacing. Where the floor consists of a customaryhydraulic Portland cement mixture, the surface may have been previouslytreated to prepare it for the troweling operation. For example, afterthe concrete has been poured and permitted to set for a given length oftime, it may be roughly surfaced as by means of a motor driven disc, anda iine clean sand applied over the surface prior to being troweled withthe present machine. The operator holds the handle I9 while the motor isin operation, and the motor rotates the entire structure l at a suitablerate, asfor example 50 to 150 revolutions per minute. The trailing edges48 of the trowel blades act upon the cementitious surface to produce asmooth and compact finish. The operator gradually progresses the machineover the entire flooring being surfaced, taking care to producesubstantially a uniform degree of troweling over all areas.

The angle of the blades l2 With respect to the plane of operation of thetrailing edges 48 depends upon the degree of hardness of the surfacebeing troweled. In general the harder the surface, the steeper will bethe angle of the blades. Such adjustments can be readily made by theoperator simply by turning the screw 28. Occasionally the blades may beadjusted individually to compensate for uneven wear, or in case a wornblade is replaced. Such individual adjustments can be made by changingthe setting of set screw 46 in conjunction with a change in the settingof nut 41, in which case the corresponding bar 39 is in effect rockedabout the spacing collar 43. If more substantial adjustments arenecessary, co1- lar 43 can be replaced with other collars of Varyingsize, or washers can be applied to change the spacing of bar 39 withrespect to the shaft.

My machine is capable of efficient troweling or floating action,particularly since it is a simple matter to have the trowels bearequally upon the surface being finished. It has been found that wherethe trowel blades do not bear equally, as for example when one trowelbears harder than the others, or when a trowel wears unevenly along itslength to bear improperly, the machine does not operate smoothly buttends to chatter, with the result that the desired smooth hard surfacecannot be obtained.

I claim:

1. In cement troweling apparatus, a rotatable structure including acentral hub, a plurality of shafts journaled by the structure andextending outwardly from the hub, blades mounted upon said shafts andarranged so that corresponding edges of the blades may operate upon acommon horizontal surface to be troweled, gears secured to the innerends of saidshafts, a ring gear within the hub and engaging said firstnamed gears, and means for rotating said ring gear to adjust the angularsetting of said ring gear with respect to the hub, whereby theinclination of each of said blades is varied.

2. In cement troweling apparatus, a rotatable structure, radiallydisposed members journalled to said structure for rotation about theirindividual axes, a plurality of radially disposed troweling bladesarranged so that their corresponding lower edges are in a common planecorresponding to the surface to be troweled, means for attaching each ofsaid blades to a corresponding member, said attaching means comprisingmeans for individually adjusting each of the blades with respect to saidplane, and means having an operating connection with each of saidmembers for simultaneously rotating said members to vary the angle ofinclination of all of the blades with respect to said plane.

3. In cement troweling apparatus, a rotatable structure, a motor carriedby the structure and adapted to drive the same, a plurality of trowelingblades associated with said structure, said blades extending indirections generally radial with respect to the axis of rotation of thestructure and being so disposed that their corresponding lower trailingedges are in a common plane corresponding to the surface to be troweled,radially disposed shafts rotatably secured to the structure, meansserving to mount each of said blades on an associated shaft, saidmounting means including elements adjustable whereby the position ofeach blade may be adjusted with re` spect to its corresponding shaft,and means for simultaneously turning all of said shafts to vary theinclination of the blades, said means including an adjustable connectionwhereby the angular setting of any one shaft can be adjustedindependently of the others.

4. In cement troweling apparatus, a structure rotatable about a verticalaxis, a plurality of radially disposed troweling blades, the bladesbeing so disposed that their corresponding lower edges are in a commonplane corresponding to the surface to be troweled, radially disposedmembers rotatably journalled to said structure, means connecting each ofsaid blades to an associated member, said means including elementsadjustable for moving each of said blades about an axis at an angle tothe radial axis of its associated member, thereby effecting anindividual adjustment of the blade with respect to said plane, and meansfor simultaneously rotating al1 of said members about their respectiveradial axes to vary the angle of inclination of all said blades withrespect to said plane.

5. In cement troweling apparatus, a structure rotatable about a verticalaxis and including a central hub, a plurality of shafts journaled on thestructure and extending outwardly from the hub, blades mounted upon saidshafts and arranged so that corresponding edges of the blades mayoperate upon a common horizontal surface to be troweled, and means forsimultaneously adjusting the angular setting of all of said shaftswhereby the inclination of the blades can be simultaneously varied, saidmeans comprising a member mounted on the structure to rotate about thevertical axis of the same, and a plurality of motion-transmittingelements secured to the inner ends of said shafts and having driveconnections with said member.

ROY A. CONWAY.

